Liquid separator

ABSTRACT

A centrifugal separator comprises a pair of centrifugal pumps of the airfoil type. A mixture of liquids of different specific gravities is fed centrally to one pump and the heavier liquid is withdrawn from the periphery of that pump. The other pump withdraws the lighter liquid from the center of the first pump and discharges the lighter liquid peripherally.

[ 1 July 17, 1973 IJnited States Patent 1 Daniel I FOREIGN PATENTS OR APPLICATIONS LIQUID SEPARATOR William H. Daniel, 54] Putman Road, Rogers, Ark. 72756 June 23, 1971 707,767 5/1941 Germany 416/185 [76] Inventor:

Primary Examiner-Samih N. Zaharna Assistant ExaminerF. F. Calvetti Alt0rney-Young & Thompson 221 Filed:

211 App]. No.1 155,767

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2 u "I. c u 4 n "u m 1 em mZ m m M4 UIF HUN 0 UNITED STATES PATENTS 3,347,371 Verbaere........................ 210/512 X 9 Claims 4 Drawing Figures 3,261,297 7/1966 Daniel 415/213 R JJFF Patented July 17, 1973 I 3,746,173

2 Sheets-Sheet l Patented July 17,1973

2 Sheets-Sheet 2 INVENTOR. MAW/am H 05 0 /'Z/ Mung 1% 7750/0 2500 LIQUID SEPARATOR The present invention relates to centrifugal liquid separators.

It is an object of thepresent invention to provide a centrifugal liquid separator in which the separation of large quantities of liquid is effected very rapidly.

Another object of the present invention is the provision of a centrifugal liquid separator that effects a relatively fine separation between the liquid components.

Finally, it is an object of the present invention to provide a centrifugal liquid separator which will be relatively simple and inexpensive to manufacture, easy to operate, maintain and repair and rugged and durable in use.

Briefly, these objects are achieved in the present invention by providing a pair of centrifugal pumps of the air-foil type one of which discharges the heavier liquid at its periphery and the other of which has its intake disposed centrally of the first-mentioned pump. As a result, the liquid mixture to be separated flows into the first-mentioned pump and the heavier liquid is discharged therefrom under the impetus of the first pump, while the lighter liquid is discharged under the impetus of the second pump.

Other objects, features and advantages of the present invention will become apparent from the consideration of the following description, taken in connection with the accompanying drawings, in which:

FIG. 1 is a somewhat schematic cross-sectional view of a liquid separator according to the present invention;

FIG. 2 is a view of the pump rotor, looking in the direction in which the feed enters the inlet;

FIG. 3 is a perspective view of the rotor of either of the pumps; and

FlG.'4 is a cross-sectional view perpendicular to the axis of the pump and showing the rotor vanes in cross section and indicating generally the direction of liquid flow.

Referring now to the drawings in greater detail, there is shown liquid separator apparatus according to the present invention, comprising a pair of centrifugal pumps 1 and 3 of the airfoil type, which may be of the type disclosed in my copending application entitled AlRFOlL VACUUM PUMP WITH TAPERED RO- TOR filed on even date herewith, to which reference is made for a more complete disclosure.

Pumps 1 and 3 may also be generally similar to each other, so that a description of one suffices for the other, except where noted.

Accordingly, each pump 1 or 3 comprises a casing 5 of tapered configuration, that is, that increases progressively in diameter in a direction away from the axially central inlet 7 toward the peripheral outlet 9, thereby to define a pump chamber 11 of generally conical configuration. Disposed in each chamber 11 is a rotor 13 comprising a shaft 15 axially disposed of the rotor with means (not shown) to rotate the shaft 15 thereby to drive the rotor and hence the pump. Shaft 15 is mounted in a bearing 17 through a side wall of easing 5, and carries at its end a circular flat plate 19 closely spaced from and parallel to the corresponding flat plate forming a portion of the casing 5. Each plate 19 carries at least one and preferably a plurality of vanes 21 thereon, each of which is mounted at its base 23 on the outer periphery of plate 19 and extends away from shaft 15 in the direction of inlet 7 and is radially inwardly inclined in a direction generally parallel to the adjacent inclined side walls of casing 5, to a tip 25. Each vane 21 is bounded by a leading edge 27 and a trailing edge 29, which converge radially inwardly, that is, in a direction away from the plate 19. Also, the thickness of each vane 21 decreases in a direction away from the plate 19 so that the airfoil cross-sectional configuration of the vane 21 at base 23 is congruent with but substantially larger than the airfoil cross-sectional configuration of vane 21 at tip 25, as can best be seen in FIG. 2.

Each vane 21 has a region of greatest thickness; and from that region of greatest thickness rearwardly to the trailing edge of the vane, the radially outer surface of the vane is concentric with the pump and parallel to the adjacent side wall of casing 5.

Accordingly, as liquid flows in the inlet of each pump, the liquid first comes under the influence of the relatively small and relatively slowly moving radially inner portions of the vanes 21 adjacent the tips 25. Because these tips 25 are relatively small and travelling at a relatively low tangential velocity, the liquid tends to be relatively little influenced by the initial portion of the rotor that it contacts. Also, the casing is at its widest adjacent the axial inlet thereto. But as the liquid moves radially outwardly, three things happen: (1 the portion of vanes 21 contacted by the liquid increases in cross sectional configuration and so the force, or rather the suction, exerted on the liquid by the vanes progressively increases;

(2) the radially farther out along the vane the liquid progresses, the higher the tangential velocity of the portion of the vane contacted by the liquid, so that the vane in effect travels progressively faster with respect to a radially outwardly moving portion of liquid, which increased velocity has the effect of increasing the pressure and velocity of the liquid; and

3. as the liquid travels radially outwardly in the pump, the radially outwardly converging side walls of the casing confine the liquid to a progressively more narrow channel, so that the liquid must travel increasingly faster by virtue of the casing configuration. As a result, the liquid progressively accelerates and progressively increases in pressure, during its path through each chamber 11 from inlet 7 to the outlet 9, whereby smooth laminar flow with high pump efficiency is achieved.

At the same time, very rapid and efficient separation is achieved, the heavier liquid being discharged from the outlet 9 of pump 1 and the lighter liquid accumulating centrally of pump 1.

The liquid to be separated is fed to pump 1 through a conduit 31 immersed in a tank 33 or other source of liquid mixture to be separated. The separated lighter component travels to the pump 3 under control of a valve 35 through a conduit 37 which is concentric with and disposed within the inlet 7 of pump 1. The liquid flowing through conduit 1 thus flows about the conduit 37 and into pump 1 for its principal separation and about an outwardly tapered annular bafile 39 at the intake end of conduit 37 and thence into conduit 37 for flow to the left as seen in FIG. 1, into the inlet of the pump 3. The lighter liquid is discharged peripherally of pump 3, there being substantially no separation in pump 3 because the separation is very largely completed in pump 1. Of course, if further separation were needed, then the outlet of pump 3 could be connected to the inlet of a further pump 1 associated with a still further pump 3, etc., through as many serially arranged separation stages as were needed.

In effect, pump 3 competes successfully with pump 1 for the lighter liquid. Therefore, the intake vacuum of pump 3 should be greater than that of pump 1, and can for example be twenty inches of Hg. as opposed to twelve inches of Hg. for pump 1. The relative flow rates and intake pressures can of course be adjusted by manipulation of valve 35.

in view of the foregoing disclosure therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

Having described my invention, 1 claim:

, l. A liquid separator comprising a pair of centrifugal pumps each having a pump chamber and an axial inlet and a peripheral outlet, means to feed liquid to be separated to said inlet of one of said pumps, means to withdraw heavier liquid from the outlet of said one pump, and means to feed lighter liquid from a central portion of the pump chamber of said one pump to the inlet of the other said pump, said one pump comprising a rotor rotatable in a casing, said rotor having at least two airfoil vanes thereon that are inclined radially inwardly in a direction toward said inlet of said one pump and away from said rotor, said casing having a side wall inclined radially inwardly in the same direction as said at least two airfoil vanes.

2. A liquid separator as claimed in claim 1, said at least two vanes having leading and trailing edges that converge in a direction away from said rotor.

3. A liquid separator as claimed in claim 2, said at least two vanes being thickest adjacent said rotor and thinnest remote from said rotor.

4. A liquid separator as claimed in claim 1, the inlet of said other pump communicating with said one pump through a conduit extending and terminating axially of said one pump, said at least two airfoil vanes axially overlying the inlet end of said conduit.

5. A liquid separator as claimed in claim 4, said inlet of said one pump being annular about said conduit.

6. A liquid separator as claimed in claim I, each of said pumps comprising a rotor rotatable in a casing whose side walls converge radially outwardly, each said rotor having at least two airfoil vanes thereon that are inclined radially inwardly in a direction toward said inlet and away from its associated said rotor.

7. A liquid separator as claimed in claim 6, said at least two vanes having leading and trailing edges that converge in a direction away from said rotor.

8. A liquid separator as claimed in claim 1, and valve means in the inlet of at least one of said pumps to reglate the flow to the inlets of the pumps relative to each other.

9. A liquid separator as claimed in claim I, the inlet suction of said one pump being less than the inlet suction of said other pump. 

1. A liquid separator comprising a pair of centrifugal pumps each having a pump chamber and an axial inlet and a peripheral outlet, means to feed liquid to be separated to said inlet of one of said pumps, means to withdraw heavier liquid from the outlet of said one pump, and means to feed lighter liquid from a central portion of the pump chamber of said one pump to the inlet of the other said pump, said one pump comprising a rotor rotatable in a casing, said rotor having at least two airfoil vanes thereon that are inclined radially inwardly in a direction toward said inlet of said one pump and away from said rotor, said casing having a side wall inclined radially inwardly in the same direction as said at least two airfoil vanes.
 2. A liquid separator as claimed in claim 1, said at least two vanes having leading and trailing edges that converge in a direction away from said rotor.
 3. A liquid separator as claimed in claim 2, said at least two vanes being thickest adjacent said rotor and thinnest remote from said rotor.
 4. A liquid separator as claimed in claim 1, the inlet of said other pump communicating with said one pump through a conduit extending and terminating axially of said one pump, said at least two airfoil vanes axially overlying the inlet end of said conduit.
 5. A liquid separator as claimed in claim 4, said inlet of said one pump being annular about said conduit.
 6. A liquid separator as claimed in claim 1, each of said pumps comprising a rotor rotatable in a casing whose side walls converge radially outwardly, each said rotor having at least two airfoil vanes thereon that are inclined radially inwardly in a direction toward said inlet and away from its associated said rotor.
 7. A liquid separator as claimed in claim 6, said at least two vanes having leading and trailing edges that converge in a direction away from said rotor.
 8. A liquid separator as claimed in claim 1, and valve means in the inlet of at least one of said pumps to reglate the flow to the inlets of the pumps relative to each other.
 9. A liquid separator as claimed in claim 1, the inlet suction of said one pump being less than the inlet suction of said other pump. 